地质学
地球化学
斜长石
奥陶纪
辉石
角闪石
磷灰石
钛矿
微量元素
岩浆
长石
辉长岩
火成岩
火山
黑云母
古生物学
石英
变质岩
橄榄石
出处
期刊:GFF
[Informa]
日期:2014-02-28
卷期号:136 (2): 387-397
被引量:11
标识
DOI:10.1080/11035897.2013.854272
摘要
A suite of metabentonites (altered volcanic ashes or K-bentonites) from the Sandbian Stage, Upper Ordovician, from Scandinavia was subjected to a detailed geochemical study which highlighted specific correlations and magmatic processes. A bimodal distribution in elemental compositions for one suite of metabentonites suggested that it was generated by magma mixing processes. There is strong evidence to correlate three Grefsen samples from Fjäcka, Sweden, with the lowermost Grefsen samples from Sinsen, Oslo, Norway. New data for rare earth element (REE) concentrations in cognate apatite microphenocrysts support the bulk trace element scenarios and confirm the role of plagioclase feldspar and pyroxene ± hornblende fractionation in the formation of eruptive magmas of intermediate composition formed during the closure of the Iapetus Ocean and Tornquist Sea in Upper Ordovician times. New REE data from apatite microphenocrysts can assist in correlating these metabentonites with contemporary beds elsewhere in Northern Europe.
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